Direct Methanol Fuel Cell (DMFC) Battery Replacement Program.

摘要

Active DMFCs require complicated balance of plant to ensure recirculation of unreacted methanol and internally produced water as well as venting of exhaust gases. An alternative approach is redesign of the fuel delivery system to accommodate concentrated methanol that is consumed entirely within the fuel cell, thus removing the need for recirculation. A specialized anodic porous structure was designed which the dual role of flowfield and diffusion medium for concentrated methanol. In addition, a highly hydrophobic gas diffusion media were used at the DMFC cathode to prevent water loss by promoting water back-diffusion to the anode. This internally dilutes the methanol and enables use of highly concentrated methanol. The anodic porous structure used in concert with the hydrophobic cathode diffusion medium led to gross fuel energy densities of the operating cell of ca. 845 W*hr/Lfuel and fuel utilization in excess of 70%. A small 2 cell stack was built and successfully operated to verify that the concept is scalable. The hydrophobicity of the cathode diffusion layer is of vital importance for this concept and research for improved materials that will reduce water loss even more is still ongoing using internal funds. The project also funded student research at Northeastern University and at Inter American University in Puerto Rico. This hardware based program complemented an IFDL modeling program sponsored by the DOE.